The Chiappa Firearms M4-22 Gen II Pro Upper is a dedicated 22 LR conversion kit designed to fit any Mil-Spec AR-15 lower receiver. It features a 16 heavy contour steel barrel with a Black Parkerized finish and a 1:16 twist rate. Constructed with a Matte Black polymer receiver, this 4 lbs assembly utilizes a 7.80 quad Picatinny rail for mounting optics and accessories. This complete upper comes with two 28-round magazines, providing an ideal platform for cost-effective training and plinking while maintaining standard AR-15 dimensions. Note: This upper receiver is specifically designed for 22 LR ammunition and is compatible with standard Mil-Spec AR-15 lower receivers for a seamless caliber conversion.